Exterior insulating sheathing

Abstract

An exterior insulating sheathing which comprises a foam polystyrene ply and a second ply glued to said polystyrene ply throughout. The second ply is preferably a fiberboard but may also be a waferboard. The sheathing is nailable, has a racking load of about 1900 to 3700 lbs, and has at least he exposed side of the second ply water resistant. This sheathing has a minimum tensile strength of 65±14 kPa, a linear expansion at 97% RH and 23° C., of less than 0.40%±0.02, a water vapor transmission of at least 96 ng .Pa.s.m 2 , and a modulus of rupture of 0.5 to 17.2 megaPascal.

I claim: 
     
       1. An exterior insulating sheathing having a good vapour transmission consisting of a foam polystyrene ply and a second ply of fiberboard, said second ply having at least one side water resistant, said second ply being glued to said polystyrene ply throughout with a continuous layer of glue, so that said continuous layer of glue is sandwiched between said foam polystyrene ply and said second ply, as to continuously fasten said polystyrene ply to said second ply, to form a unitary product defining an exterior insulating sheathing, said exterior insulating sheathing having said at least one water resistant side of said second ply forming one of the exposed side of said exterior insulating sheathing, said exterior insulating sheathing being nailable and mountable on supporting beams and having a racking load according to ASTM E-72 of about 2100±200 lbs, a minimum tensile strength of 65±14 kiloPascal, a linear expansion at 97% relative humidity and 23° C., of less than 0.40%±0.02, a water vapour transmission of at least 96 nonagram per second per meter square ( ng  /Pa.s.m 2 ), and a modulus of rupture of 0.6±0.1 megaPascal (mPa). 
     
     
       2. The sheathing as defined in claim 1 wherein said polystyrene ply has a density of about 0.6 lbs/cu ft to 1.4 lbs.ft 3  and wherein the thickness of said polystyrene is 1.5±0.5 inch, and the thickness of said fiberboard ply is about 7/16 to 8/16 inch to form a unitary sheathing of about 2 inches in thickness. 
     
     
       3. The sheathing as defined in claim 2 wherein said fiberboard ply is about half an inch, said polystyrene ply about an inch and a half, and has a density value of 1±1 lb/ft 3 , and the sheathing has a R value of 6.5±0.3 Imperial unit (ft 2 , hr, oF/Btu) as per ASTM C518. 
     
     
       4. The sheathing as defined in claim 1 wherein the exposed said at least one water resistant side of said second ply is asphalt coated. 
     
     
       5. The sheathing as defined in claim 1 wherein the second ply is an asphalt impregnated fiberboard ply. 
     
     
       6. The sheating as defined in claim 1 having at least one ship lap.